800 amp service

[Greg1707]

This is a service for five new townhouses. Each meter has a 200 amp breaker on the load side. The enclosure on the right has a label on the top left corner: "800 amps MAX." Is this setup OK?

 

[electricalist]

What size are the service conductors to each meter?

 

[iwire]

This is a service for five new townhouses. Each meter has a 200 amp breaker on the load side. The enclosure on the right has a label on the top left corner: "800 amps MAX." Is this setup OK?

As long as the total calculated load is under 800 amps the meter set up is fine. The service conductors would also have to be rated for the calculated load.

The breaker sizes don't matter here.

 

[electricalist]

If the OP doesn't mind.
If the calculated load is 800 or under and conductors are 800. What happens when someone adds to the load or adds the other meter and doesn't change the service conductors.?

 

[augie47]

As long as the total calculated load is under 800 amps the meter set up is fine. The service conductors would also have to be rated for the calculated load.

The breaker sizes don't matter here.

Agree. It's a very common set-up in this area

If the OP doesn't mind.
If the calculated load is 800 or under and conductors are 800. What happens when someone adds to the load or adds the other meter and doesn't change the service conductors.?

The Code expects that the "someone" determines the existing and added load and
act accordingly. No different from many MLO service panels.

 

[electricalist]

This part of services rattles me every time. I think I understand how its ok yet I keep saying . Thats a bad idea. In a black and white way it makes more sense to me that the 200 amp breakers would need to be what the load is and the service conductors would need to be 800 amp size. The taps to each meter being 150 or no more than 200 amp size.

 

[Greg1707]

800 amps or 1000 amps

800 amps or 1000 amps

Ok, my questions is about the label that states 800 amp max. What does that mean? Is this an 800 amp service or a 1000 amp?
Why are there five two hundred amp breakers and the enclosure states 800 amp MAX?

 

[electricalist]

Sincerely my apologies. Greg 1707.

 

[Cow]

Ok, my questions is about the label that states 800 amp max. What does that mean? Is this an 800 amp service or a 1000 amp?
Why are there five two hundred amp breakers and the enclosure states 800 amp MAX?

Again:

As long as the total calculated load is under 800 amps the meter set up is fine. The service conductors would also have to be rated for the calculated load.

The breaker sizes don't matter here.

 

[iwire]

Ok, my questions is about the label that states 800 amp max. What does that mean? Is this an 800 amp service or a 1000 amp?

800 amps is the maximum current the bus bars in that right hand cabinet can carry.

As far as the 'service size' I can't tell you. The service conductors supplying this might only be rated 700 amps. They only have to be large enough to supply the NEC calculated load at the time of installation.

For instance if each town houses calculated load was 125 amps, five times 125 would only total 625 amps so the service conductors would only have to be rated 625 amps.

Why are there five two hundred amp breakers and the enclosure states 800 amp MAX?

Because exception 3 of 230.90(A) allows this and it is a good way to save money.

Exception No.3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.

 

[kwired]

Can't say I am familiar with Eaton's products, but that mains cabinet is likley available in 200, 400 and 600 amp versions as well. So whoever installed this must have had a load calculation of 600 or more or figured that if the last meter were ever used it could go over 600.
Otherwise they probably would have saved some $$$ if load calc were only 340 amps and they would have chosen a 400 or 600 amp main section.

I installed a I-Line panel a while back - 800 amp bus, used the six service disconnect rule so all breakers in the panel were "mains" had a calculated load (including expected future load) of around 650 amps. The breakers installed were two 400 amp breakers and two 125 amp breakers. The main lugs kit that the service conductors landed on were rated for 1200 amps though they only had 750 amps of supply conductors landed on them, and were connected to an 800 amp rated bus.

What "size of service" was that install? The breakers added up to 1050, the bus was only rated for 800, the main lugs were rated 1200. Calculate load however was only 650. On my permit application I guess it was 600-800 amps because that is the choices on the application, but if being precise I guess it would have been 750 as that is the maximum design the entire setup could possible handle.

One 400 amp breaker was for a future chiller to be installed in a couple years, but until they add that load, I'd bet you can go in that place at just about any time and take a current reading and seldom ever get a reading over 100 amps.

 

[electricalist]

Look familuar Mr.Kwired

 

[kwired]

Look familuar Mr.Kwired

Familiar - maybe not, at least not to the same details, but yes what you have there is NEC compliant if the calculated load is 1600 amps or less - and any details of listing of the switchgear are followed. I believe a switchboard will have less complications with such details, but a panelboard can have more details you need to look into. The one I mentioned in my installation earlier was listed to be used with up to six mains, but that is not always true with panelboards - especially the smaller packaged "loadcenters", most of those do require a main breaker or overcurrent protection ahead of the panel.

 

[electricalist]

My bad. I thought this was a digram you sent me showing how the service can be smaller than the sum of what it feeds.

 

[Dennis Alwon]

My bad. I thought this was a digram you sent me showing how the service can be smaller than the sum of what it feeds.

It is not the feeder size but the calculated load that is important.

Look at a 200 amp panel filled with 40 sp 20 amp breakers. Let's say this is residential and controls all the 120 circuits in the house. This panel will probably never see more than 60 amps even though the breakers total to be 800 amps.

 

[Nom Deplume]

200 amps per townhouse? sounds a little oversized to me unless they have a lot of electric appliances.

 

[meternerd]

Does the POCO consider it an 800A service? Utilities size their service wires based on expected load given by the customer, not necessarily the breaker size. If they lowball the rating, overheating and fire can result. Likely the same deal here. Sized for expected load. Could the load eventually exceed the bus rating. Sure. I've seen many meter cans melted due to excessive load. Usually commercial where multiple service disconnects are installed.

 

[augie47]

Does the POCO consider it an 800A service? ...................

Makes no difference. They will feed it with a #2 ACSR (joking with a small element of truth)

 

[iwire]

It is not the feeder size but the calculated load that is important.

Look at a 200 amp panel filled with 40 sp 20 amp breakers. Let's say this is residential and controls all the 120 circuits in the house. This panel will probably never see more than 60 amps even though the breakers total to be 800 amps.

If you bring feeders into this it just confuses the issue, we are talking about service conductors and the rules are different.

 

[Dennis Alwon]

If you bring feeders into this it just confuses the issue, we are talking about service conductors and the rules are different.

My reference was the six feeder overcurrent protective device. I see that as part of the question. The feeders make up the load for the service.